Advances in fiber optic interconnection technology have opened numerous and diverse commercial applications. Industry standards and conventions have evolved along with the technology, and these standards govern optical systems to some extent. Nevertheless, each new fiber optic application comes with unique requirements, and existing optical system components must be adapted accordingly. It follows that there is a strong need for more flexible components which can accommodate a variety of applications.
However, a three-way balance arises between the above-described need for flexibility, an equally important need for economy, and an overriding need to comply with industry standards.
Prior attempts to strike the proper balance have resulted in a variety of "universal" optical components which may be adapted to different applications.
For example, in U.S. Pat. No. 4,979,792 issued to Weber et al., a connector is disclosed with interchangeable keying elements to allow field keying to the correct plug assembly. U.S. Pat. No. 5,117,476 issued to Yingst et al., discloses an optical package including a receptacle shell having a field keying system. Keying means such as the ones described in the patents eliminate the risk of connecting an improper plug to the receptacle when numerous identical plugs and receptacles exist.
Even more flexibility and economy could be achieved by an adapter which facilitates mating of a variety of optical plugs with different receptacles, for instance, plugs and receptacles having different configurations and/or conforming to different industry standards. When combined with the field keying feature disclosed in Weber et al. '792, the resulting "universal" connection capability would be extremely useful in optical systems which adhere to different connector conventions.
However, industry and design standards require optical transmission accuracy and low signal losses, and these qualities are easily compromised in a universal-type connector. Specifically, transmission accuracy is decreased and signal losses are increased by non-precision alignment of the optical fibers which are joined at the connector. Such misalignment may occur initially at assembly, or it may result from subsequent instability in the field.
Past attempts at universal-type connectors have too often sacrificed quality and stability of optical fiber alignment. Consequently, a clear commercial need exists for an adapter which mates optical fiber plugs with dissimilar receptacles.